Modelling the effects of Climate Change on dairy farms: an integration of livestock and economic models

Climate Change (CC) may increase the incidence of heat stress on dairy cattle, sharpening the reduction of daily milk production and the drop of its quality (decrease of percentage fat and protein content and increase in somatic cells counts). It may also increase the rate of annual mortality of livestock. On the other side, CC itself and these effects can also change nutritional requirements of the herd. This paper discusses the approach by means of which all these aspects were integrated into a model of Discrete Stochastic programming (DSP), representing the decision making and the related income results in the short term in dairy farms. The functional relationships between conditions of temperature and humidity and the productive performances of dairy cattle are reconstructed on the basis of specific studies conducted in the Po Valley. The same for mortality rate. The effects of production performances on nutritional requirements of the herd are estimated with the mathematical model CNCPS, which also takes into account the influence of climatic conditions. These parameters are then used as inputs for the DSP model, whose structure is based on the assumption that the breeder considers them in planning land use of the farm for the production of forage and grain crops. The model also simulates the amount and composition of purchased feed for completely satisfying nutritional requirements of the herd. The comparison between the results of the DSP model, with productive performances and feed purchasing under current and future climate, indicates the possible management and income effects of CC